The RX-7 Body Electric Manual shows the low coolant buzzer as being a function of the CPU2, but in the list of pins and their functions, I do not see the coolant sensor mentioned. What gives? Does anyone know which pin it is?

I know that I don't have low coolant, and I have continuity between the sensor and the correct pin on the grey connector next to the battery...But after that, I can't trace it in the harness because I can't figure out which pin it is on the CPU2.

-James

 

Had the same problem on my FD. Turned out to be a single wire connector on the left side of the engine that was disconnected. Have a close look in that area.

 

Thanks for the reply... I think everything is connected properly since I do have continuity from the sensor to the big blocky grey connector above the driver's side fender liner. Are you saying that there are two paths that must be connected? That seems weird since from my understanding, all the CPU2 is doing is looking to see if the coolant level sensor is grounded (has water around it).

 

I think the info I've asked for here would still be useful to someone, if anyone knows the answer...But I've solved my particular problem. I had a loose connection at the grey connector (brown/white stripe wire). It might have been a corroded pin or something similar.

 

According to page Z-42 of my 1994 FWM (not the Body Electrical manual), the coolant level sensor does not go to CPU2. The signal path runs from the sensor (on a black wire in the Emission Harness) to the Engine Harness, through connector C-06. There the wire changes to a brown/white wire and runs through connectors X-12 and X-06 to terminal 3D of the Instrument Cluster. Inside the Instrument Cluster there is a "CPU and Speedometer" block, and the signal runs there. The output from the Instrument Cluster's internal CPU then (apparently; line is shown but not identified) runs to the "Coolant" alarm light in the cluster.

There are unidentified lines from the Instrument Cluster's CPU running to CPU #2, notably the brown wire to terminal 1L of CPU #2, but who knows what that is?

 

Thank you very much.

My loose wire that I mentioned above went loose again somewhere inside the harness so I am buzzing again...

I made a jumper wire to go from the coolant level sensor blade connector to the large connector on the CPU2, and I tried to touch it to every pin, but the buzzing did not stop. So by that, I ascertained what you have stated: The CPU2 does not determine when the buzzing happens, it only buzzes when it is told to by another component.

I know everyone is sick of coolant buzzer threads because there have been a million of them. This one is different because until now I have not seen a thread in which it was stated that the CPU2 does not control when the buzzing happens (maybe I missed it in my searches...) This is a useful piece of information that someone can find in future searches.

Thanks again.